Time-division multiplexing of polarization-insensitive fiber optic michelson interferometric sensor

摘要

This invention concerns with a time-division multiplexing system of polarization-insensitive Michelson interferometric fiber optic sensors, where the compensating interferometer is equipped with a 3. times.3 coupler. It uses the two reflections from the Faraday rotator mirrors of sensor interferometer and compensating interferometer, respectively, in a totally passive manner, to overcome the polarization- induced signal fading in the multiplexing sensor system. The compensating interferometer with matching optical paths is used to reduce the phase- induced intensity noise, at the same time it allows the use of laser source with proper coherence length to reduce the crosstalk between sensors and the crosstalk caused by Rayleigh scattering. This system allows the use of low-loss conventional single-mode optic fiber as lead fiber, and offers advantages in building the fiber optic sensor array system with long- distance lead fiber. Furthermore, this system is characteristic of good performance on lead fiber insensitivity. The use of 3×3 demodulation circuits increases the sensor bandwidth significantly without increasing the sampling rate.